Hey Daryl! Given how off track this thread has gotten (now it seems to be the caterpillar song/kids songs thread), maybe you should just mail me directly. If I do end up recording something, it would be cool to have a couple of surprises. Right?
To answer your question, if I bookend the song with caterpillar verses (which I forgot to include in the previous count oops!) then the animals I have so far are caterpillar, gator (because crocodile is too many syllables), poodle, rhino (needs reworking), snake and spider. I'm also cooking one for frogs, beetle. I like your suggestions of kangaroo (but that's three syllables too - quokka might work). Hippo is good. Galah might work too. Now you've got me thinking of Aussie native animals.
My main suggestion was just have fun with it. Go for fun, offbeat, and a little absurd; things kids could relate to and/or find amusing. You can see how easy it is to make up lyrics for a kid's song just by sticking to a formula and using rhymes. I'm sure the same applies to more serious songs too.
Write me with any other suggestions so we don't infest the forum with caterpillars.
It's been fun.
Shel